Gerrit Jan Mulder's influence upon the natural scientific research in the Dutch East Indies The well-known Dutch chemist Gerrit Jan Mulder (1802-1880), professor of chemistry at Utrecht University (1840-1868), did not only important scientific work, but was also concerned with natural scientific research in the Dutch East Indies. Already during his stay in Rotterdam, where he was a physician and lecturer of chemistry and botany at the Clinical School (1828-1840), he carried out chemical investigations for the Nederlandsche Handel-Maatschappij (Dutch Trade Company) on the quality of different kinds of opium (1834) and of Javanese and Chinese tea (1835). Later he became scientific advisor to the Ministry of the Colonies. In 1845 Mulder was charged with the theoretical and practical training of pharmacists for the army medical corps in the Dutch East Indies. Some of his students did practical chemical research at the chemical laboratory of the army medical corps at Weltevreden (Batavia, now Jacarta). One of his Ph.D. students, P.F.H. Fromberg, founded an agricultural chemical laboratory at Buitenzorg (now Bogor, 1851); others (J.H. Croockewit, C.L. Vlaanderen) went to the Dutch East Indies as a chemist, charged with the improvement of the tin production; while K.W. van Gorkom was appointed chemist for the cinchona culture. These researches were aimed at the practical applicability of chemistry: chemical analysis of minerals and mineral waters, investigations of trees and roots after the presence of therapeutic constituents, research on cinchona, and so on. With these activities chemists and pharmacists, trained by Mulder at his Utrecht chemical laboratory, did contribute to the inventory of the richness the Dutch East Indies had to offer.